DIGITAL Fortran includes several directives that support High Performance Fortran (HPF), an extended version of Fortran 90 for parallel programming. DIGITAL Fortran supports parallel execution of HPF programs on clusters of DIGITAL UNIX systems with Digital Parallel Software Environment (PSE) installed. Parallel execution can increase performance.

On OpenVMS, Windows NT and Windows 95 systems, and in programs compiled without the -wsf option on DIGITAL UNIX systems, the HPF directives are parsed and checked for syntactic errors, but have no effect on program execution.

HPF directives are preceded by a special prefix that identifies them to the compiler.

There are two kinds of HPF directives: specification and executable. Specification directives must appear in the specification part of a scoping unit. Executable directives must appear in the execution part of a scoping unit.